๐Ÿซ˜ Kidney Stone Detection CNN โ€” Clinical Evaluation Report

Model: EfficientNet-B4 with custom classification head
Date: February 21, 2026
Dataset: 12,446 images (CT + Ultrasound) | Test set: 1,904 images
Status: โœ… All clinical KPI targets exceeded

Key Performance Indicators

100.0%
Sensitivity
(Target โ‰ฅ 92%)
99.2%
Specificity
(Target โ‰ฅ 88%)
1.0000
AUC-ROC
(Target โ‰ฅ 0.95)
0
False Negatives
(Missed Stones)

Confusion Matrix & ROC Curve

The ROC curve shows perfect discrimination (AUC = 1.0). The confusion matrix confirms zero missed stone cases across all 224 stone images in the test set.

Grad-CAM Visual Explanations

Grad-CAM++ heatmaps show which image regions drove each prediction. Red/yellow areas = high model attention. These should correspond to kidney and urinary tract anatomy for valid predictions.

False Positive Analysis (14 cases)

All 14 false positives are shown below with Grad-CAM overlays. These are no_stone images incorrectly predicted as stone. Common causes: cysts mimicking stones, vascular calcifications, image compression artifacts.

Clinical impact: These 14 cases would trigger unnecessary follow-up imaging but would not cause harm. Zero false negatives means zero missed stones โ€” which is the primary safety requirement.

Threshold Calibration

Decision threshold was optimised using F2-score on the validation set. F2 weights recall (sensitivity) twice as heavily as precision, appropriate for a screening tool where missing a stone is more harmful than a false alarm.

Detailed Metrics Table

MetricValueTargetStatus
Sensitivity (Recall)1.0000โ‰ฅ 0.92โœ… PASSED
Specificity0.9917โ‰ฅ 0.88โœ… PASSED
AUC-ROC1.0000โ‰ฅ 0.95โœ… PASSED
Precision0.9412โ‰ฅ 0.85โœ… PASSED
F2-Score0.9877โ‰ฅ 0.90โœ… PASSED
False Negatives0Minimiseโœ… ZERO
False Positives14< 5% of negativesโœ… 0.83%

Known Limitations

Next Steps โ€” Phase 4

Model is ready for API development and deployment. Phase 4 will wrap this model in a FastAPI REST endpoint, containerise with Docker, and serve predictions with Grad-CAM heatmaps via HTTP.


Generated automatically by scripts/generate_report.py ยท 2026-02-21 21:19 ยท Kidney Stone CNN v1.0